body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f0f2f5;
}

nav, .sub-nav, .filter-bar {
    background-color: white;
    padding: 10px;
    margin-bottom: 10px;
}

.nav-items, .sub-nav {
    display: flex;
    gap: 20px;
}

.nav-item, .sub-nav-item {
    cursor: pointer;
}

.sub-nav-item.active {
    color: #3498db;
}

.filter-bar {
    display: flex;
    gap: 10px;
    align-items: center;
}

select, input {
    padding: 5px;
    border: 1px solid #ddd;
    border-radius: 4px;
}

.icon-button, .random-button {
    padding: 5px 10px;
    background-color: #f0f2f5;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}

.random-button {
    background-color: #3498db;
    color: white;
}

table {
    width: 100%;
    border-collapse: collapse;
    background-color: white;
}

th, td {
    padding: 10px;
    text-align: left;
    border-bottom: 1px solid #ddd;
}

.pagination {
    display: flex;
    justify-content: center;
    margin-top: 20px;
    gap: 5px;
}

.pagination button {
    padding: 5px 10px;
    border: 1px solid #ddd;
    background-color: white;
    cursor: pointer;
}

.pagination button.active {
    background-color: #3498db;
    color: white;
}

.problem-link {
    text-decoration: none;
    color: #3498db;
}

.problem-link:hover {
    text-decoration: underline;
}

#problem-table tbody tr:hover {
    background-color: #f5f5f5;
}